Louis R. D'Abramo

A successful purified diet for the culture of juvenile lobsters: The effect of lecithin

Abstract A purified diet that provides excellent survival (≥ 85%) and good growth of juvenile lobsters (Homarus americanus and H. americanus × H. gammarus hybrids) through 120 days is presented. When various natural foods (frozen shrimp tails, frozen mussel, frozen liver, and live Artemia salina) are substituted for the purified diet every fourth day, the Artemia supplement produces significantly greater increases in wet weight after 90 days of growth than the other supplements. The inclusion of soy lecithin in the purified diet is critical. Its absence reduces survival dramatically (55% survival within 30 days). Investigations reveal that different forms of lecithin have variable effectiveness and that choline, a significant constituent of lecithin, is probably not the active component. An optimal vitamin mix level for this artificial diet has been determined. The artificial diet has practical application for crustacean aquaculture.

Polyunsaturated fatty acid nutrition in juvenile freshwater prawn Macrobrachium rosenbergii

Abstract Weight gain and survival responses and analyses of fatty acid composition of tissue were used to investigate the nutritional value of C18 and C ≥ 20 polyunsaturated fatty acids (PUFA) provided to juvenile Macrobrachium rosenbergii in a purified diet. Treatments consisted of isonitrogenous and isoenergetic diets that contained graded levels of pure triglycerides of 18 : 3 n −3 (trilinolenin), 18 : 2 n −6 (trilinolein), 22 : 6 n −3 (tridocosahexaenoin) and 20 : 4 n −6 (triarachidonin), alone or in combination, or pure methyl esters of C≥20n−3. All diets were formulated to contain a total of 6% lipid. A diet containing only saturated (14 : 0, 16 : 0, 18 : 0) and monounsaturated (16 : 1 n −7, 18 : 1 n −9) fatty acids as lipid sources, in proportions similar to that found in a 2 : 1 cod liver oil/corn oil mixture, served as a conditioning and control diet. Qualitative and quantitative fatty acid composition of freshwater prawn tissue generally reflected that of experimental diets. Levels of some monounsaturated and saturated fatty acids appeared to change relative to additions of PUFA. Levels of 18 : 3 n −3, 20 : 5 n −3 and 20 : 4 n −6 were conserved in the polar lipid of the whole body tissue when they were not provided in the diet. Levels of n −3 PUFAs decreased in the neutral lipid of the whole body when not provided in the diet whereas levels of n −6 PUFAs remained unchanged or increased. After feeding trials of 135 and 150 days duration, a definite qualitative requirement for 18 : 3 n −3 and/or 18 : 2 n −6 could not be determined by evaluation of weight gain response. No significant differences in weight gain of prawns fed diets containing 18 : 3 n −3 or 18 : 2 n −6 PUFA at comparable levels were apparent. There was no evidence of de novo synthesis of 18 : 3 n −3 or 18 : 2 n −6. A dietary source of C≥20n−3 or n −6 fatty acids is required by juvenile prawns as indicated by significant increases in weight gain of juvenile prawns. At the termination of the feeding trials, mean weights of prawns fed diets containing C≥20n−3 or n −6 fatty acids were 30.3 to 95.3% greater than the mean weight of prawns of the control group. Most of the juvenile groups fed the C ≥ 20 PUFA containing diets had significantly greater weight gains than those fed the 18 : 3 n −3 and/or 18 : 2 n −6 diets. Diets containing either 22 : 6 n −3 or 20 : 4 n −6 HUFAs at levels ranging from 0.075% to 0.60% were equally effective. Juvenile M. rosenbergii have an extremely limited ability to convert C18 to C ≥ 20 fatty acids in the n −3 (linolenic) and n −6 (linoleic) families. There was evidence of the synthesis of 20 : 5 n −3 from 22 : 6 n −3. Examination of the combined percentage of C ≥ 20 PUFAs of the polar lipids from whole body tissue may assist in evaluating nutritional status relative to these essential fatty acids. Results suggest that n −6 and n −3 PUFA have different metabolic functions and that some distinct differences in the polyunsaturated fatty acid nutrition exist between the freshwater prawn and marine shrimp species.

Nutritional requirements, feed formulation, and feeding practices for intensive culture of the freshwater prawn Macrobrachium rosenbergii

Abstract Research results concerning nutrition of the freshwater prawn Macrobrachium rosenbergii and applicability to the production of feed for intensive culture are presented. Future research approaches are recommended and comparisons to the nutrition of penaeid shrimp species are provided. Quantitative requirements of essential amino acids for M. rosenbergii are undefined; however, arginine, methionine, and lysine are suspected as being the first limiting amino acids in commercially formulated feeds. The proportion of each essential amino acid in the tissue of shrimp provides a good guideline for the determination of dietary requirements. Optimal dietary protein: energy ratios in shrimp feeds appear to be dependent on the ability to digest carbohydrates. The digestibility of potential protein sources in commercial feeds needs to be evaluated through in vitro studies using natural enzyme extracts. Levels of lipids in freshwater prawn diets can be as low as 2% if sufficient dietary energy is available an...

Response of juvenile freshwater prawn, Macrobrachium rosenbergii, to different levels of a cod liver oil/corn oil mixture in a semi-purified diet

Abstract Two separate experiments were conducted to determine the level of a dietary cod liver oil/corn oil (2:1, w/w ) mixture needed for maximum weight gain of juvenile freshwater prawns, Macrobrachium rosenbergii . Seven isoenergetic and isonitrogenous purified diets with levels ranging from 0 to 12% in 2% increments were evaluated in each experiment that began with newly metamorphosed postlarvae. Diets used in the first experiment had protein and estimated digestible energy levels that were slightly higher than those used in the second experiment. After termination of both experiments, juveniles receiving the diet without the oil addition had significantly lower weight gains. Significant differences in weight gain responses to different levels of lipid were identified. Some relationships differed between experiments. Neither survival nor the time interval between molts was influenced by the level of the oil mixture. A dietary lipid level ranging from 2 to 10% under a wide range of dietary lipid:carbohydrate ratios appears to be satisfactory, indicating that juvenile freshwater prawns do not require a specific level of dietary lipid. Rather, the optimal amount of dietary lipid depends upon the amount and quality of dietary protein, the level of available dietary energy, and satisfaction of specific fatty-acid requirements.

Effect of dietary protein:energy ratio on intake, growth and metabolism of juvenile green abalone Haliotis fulgens

Abstract Juvenile green abalone Haliotis rufescens were grown under laboratory conditions at 21±1 °C and fed formulated diets consisting of different protein:energy ratios (mg protein/kcal), 62, 74, 85, 100, 108, for 60 days. The level of crude protein ranged from approximately 26% to 44% while the energy content remained constant at about 4.1 kcal g −1 . Growth ranged from 3.63 to 12.33 mg day −1 . The growth of abalone fed the 100 and 108 diets was significantly greater than that of each of the other diets. Protein efficiency ratio increased as the dietary protein content increased except for the T108 diet (44% crude protein). Abalone apparently consume food to satisfy an energy requirement. Caloric expenditure due to metabolism was estimated for abalone fed diets with protein ratios of 62, 85, 100. Energy loss due to respiration did not vary appreciably among abalone fed the different diets. The proportional distribution of dietary energy into fecal, digestible, growth, and metabolic energy was estimated for abalone fed these diets. Apparent dry matter digestibility was among the lowest for abalone fed the 100 P:E diet, but growth of abalone fed this diet was significantly higher than that of each of the other treatments except the 108 diet. Unexplained energy loss to achieve balance ranged from 7% to 28.5%, some of which is probably due to differential mucus and ammonia production. Results suggest a potential for the reduction of both dietary protein and lipid without causing any adverse effects on the growth response.

Growth and survival of zebrafish (Danio rerio) fed different commercial and laboratory diets.

The need to develop standardized diets to support zebrafish (Danio rerio) research is supported by the knowledge that specific dietary ingredients, nutrients, or antinutritional factors in diets have been shown to affect development and growth of adult D. rerio and their offspring. In this study, there were seven dietary treatments consisting of five commercially available diets and two laboratory-prepared diets, three replicates per treatment. Fish were fed ad libitum twice daily for 9 weeks. At 9 weeks, both weight and length were recorded to determine condition indices. D. rerio fed one of the laboratory-prepared diets had significantly higher weights than individuals fed any of the other diets and exhibited significantly higher lengths than those fed five of the six remaining diets. Although there were significant differences in general growth demographics (length/weight) after the 9-week feeding trial, no significant differences in overall health of D. rerio were observed for the different dietary treatments as determined by statistical analysis of condition factor indices (K = [weight x 100]/length(3)). The success achieved with the laboratory-prepared diets represents the foundation for establishing an open-formulation nutritional standard to ensure that the D. rerio model for research does not generate confounding research results caused by nutritional vagaries.

A re-evaluation of the lecitihin and cholesterol requirements of juvenile lobster (Homarus americanus) using crab protein-based diets

Abstract Juvenile lobsters (Homarus americanus) were fed purified diets containing three levels of refined soy lecithin, 0, 3 and 6%, each tested in combination with four levels of supplemental cholesterol, 0.00, 0.25, 0.50 or 1.00%. All diets contained 50% purified protein derived from cooked, “deshelled”, whole rock crab (Cancer irroratus). Regardless of the dietary level of lecithin all diets without supplemental cholesterol resulted in total mortality within 14 weeks. There was no significant effect of dietary lecithin on growth or survival at any level of supplemental cholesterol. Implications of these results in light of the previously reported dietary requirement of lobsters for lecithin are discussed.

Relative prawn production and benthic macroinvertebrate densities in unfed, organically fertilized, and fed pond systems

Abstract Relative prawn production rates in unfed, organically fertilized, and fed pond systems were evaluated. Populations of benthic macroinvertebrates that potentially serve as forage organisms in these systems were also evaluated and compared with ponds without prawns to evaluate forage preferences. Juvenile prawns (x = 0.36 ± 0.02 g) were stocked into nine 0.04 ha ponds at a density of 39 520 ha −1 . Prawns in three ponds were not fed, prawns in three ponds were fed a complete diet, and three ponds received organic fertilization. Three additional ponds (0.02 ha) served as controls (not stocked with prawns and received no nutrient input). Survival averaged 86%, overall, and was not significantly different among treatments. Average weights of prawns fed complete feed or raised in fertilized ponds (36 and 33 g, respectively) were not significantly different ( P > 0.05). Prawns in unfed ponds were significantly ( P ≤ 0.05) smaller (13 g). Average prawn yields in fed, fertilized, and unfed ponds (1261, 1056, 426 kg ha −1 , respectively) were all significantly different ( P ≤ 0.05). In ponds receiving no nutrient input, macroinvertebrate densities were significantly higher ( P ≤ 0.05) in ponds without shrimp (controls) than in those stocked with shrimp. In ponds stocked with shrimp, macroinvertebrate densities in fed and fertilized treatments were significantly greater ( P ≤ 0.05) than in the unfed treatment, but not significantly different ( P > 0.05) from each other. Insect taxa showed a greater negative response to prawn predation than non-insects. Non-insect taxa demonstrated a more positive response to fertilizer and feed than insects. Although prawn production in organically fertilized ponds was surprisingly high (>1000 kg ha −1 ), economic analysis demonstrated higher net returns when prawns were fed a prepared diet, principally due to the production of greater numbers of large, high value prawns.

Effect of triacylglycerols in formulated diets on growth and fatty acid composition in tissue of green abalone (Haliotis fulgens)

Abstract Isocaloric formulated diets containing four different sources of triacylglycerols (olive, corn, linseed and cod liver oils) at three levels (1.5%, 3.0% and 5.0%, total added dietary lipid=5.0%) and a crude protein content of 37.5% to 39.9% were fed to juvenile green abalone ( Haliotis fulgens ). Growth and fatty acid composition of the muscle tissue were compared to that of abalone fed a reference diet that contained no added lipids (0.25% total lipids). After 75 days of culture in a flow-through system, no significant differences in growth were found among abalone fed the different oil types. Responses to different dietary levels of lipid were significantly different but not to sources of oils. Maximum growth was achieved at a 1.5% inclusion of oil sources. It appears that abalone have a great capacity to synthesize lipid from carbohydrate sources. Results also suggest that abalone are capable of desaturation and elongation of 18 C polyunsaturated fatty acids (PUFAs) of the n −3 and n −6 family to 20:5 n −3 and 20:4 n −6. Synthesis of 22:6 n −3 from 20:5 n −3 is not reflected in the results. The lack of a growth response to the different levels of highly unsaturated fatty acids (HUFA) provided by the different oils included in the experimental diets may be due to an insufficient duration of the experiment to achieve an essential fatty acid deficiency. The relationship between fatty acid profiles of tissue and the diets fed to the abalone suggests that metabolic activity of the gut microflora is not a source of essential fatty acids.

A successful microbound diet for the larval culture of freshwater prawn Macrobrachium rosenbergii

A high moisture (63–71%), semi-purified microbound diet containing alginate was compared to newly hatched live Artemia nauplii as an exclusive diet for the culture of larval freshwater prawn Macrobrachium rosenbergii from 5th stage (weighted mean) through metamorphosis to postlarva. Two separate trials, representing larvae from different hatches, were conducted. Larvae were stocked at 50/l into cone-shaped vessels that contained 2 l of 12‰ seawater and were part of a temperature-controlled (28 °C) recirculating culture system. Larvae were manually fed either the live Artemia diet or the microbound diet exclusively, several times daily. After 14 days (23 days post-hatch (dph)), growth of larvae fed the microbound diet was 90% of that achieved for larvae fed newly hatched nauplii of Artemia. Survival of larvae fed the microbound diet was 77.3% and 73.3%, and was not significantly different from that of Artemia-fed larvae. Composed of readily available ingredients, the diet contains 46.2% crude protein and 37.4% lipid, is easy to prepare, and has good water stability. The diet is an economically practical alternative to the fluctuating cost, nutrient uncertainty, and labor associated with the use of Artemia nauplii hatched from cysts. The characteristics of the diet suggest good potential for successful use in the larviculture of other fish and crustacean species, in either the existing or a modified state.